Amido-bis-imidazolines in lubricating oil compositions



United States Patent 3,152,080 AIVHDD-BIS-IMEAZGLINES IN LUBRICATING 01LCGMPOSI'I'EONS rank A. Stuart, Qrinda, and Warren Lowe, Berkeley,Calif., assignors to California Research Corporation,

San Francisco, Calif., a corporation of Delaware No Drawing. Filed May31, 1960, Ser. No. 32,573 2 Claims. (Cl. 252-515) This inventionpertains to lubricating oil compositions having incorporated thereinmetal-free detergents. These metal-free detergents are certainparticular imidazoline compounds.

lrnidazolines are variously well known in the art. For example, U.S.Patent 2,907,646 describes the use of 1,2 disubstituted imidazolines inamounts less than 0.005%, by weight, as a synergist in combination withtall oil to inhibit rusting by fuel oils. U.S. Patent 2,622,067describes mononuclear imidazolines as emulsifying agents foremulsifiable oils. Again, certain mononuclear imidazolines are describedin U.S. Patents 2,839,371 and 2,922,707 as additives for gasolinecompositions. However, these imidazolines of the prior art do notencompass the particular imidazolines described in detail hereinbelowand which are significantly effective as detergents in lubricating oilcompositions.

Present day internal combustion engines operate at high speeds and highcompression ratios. Vfhen used in the so-called city stop-and-godriving, which includes the greater part of the driving condition for alarge percentage of todays automobiles, the internal combustion enginesdo not reach the most efficient operating temperature. Under citydriving conditions, large amounts of partial oxidation products areformed, and reach the crankcase of the engine by blowing past the pistonrings. Most of these partial oxidation products are oil insolublepolymeric products which tend to form deposits on pistons, piston rings,etc. These deposits markedly reduce the efficiency of engine operations,and cause excessive wear and loss of power. For the purpose ofpreventing the deposition of such products, it is necessary toincorporate detergents in the lubricatin oil compositions, thus keepingthese polymeric products highly dispersed in a condition unfavorable fordeposition on metals.

For the most part, the various detergents which are added to lubricatingoils to reduce this formation of sludges and varnishes are metal organiccompounds, particularly those compounds wherein the metal is linked toan organic group through an oxygen atom. Although these metal-containingorganic compounds have some effectiveness as detergents for dispersingthe precursors of deposits within the oil itself rather than permittingthem to form added deposits on the engine parts, they have thedisadvantage of forming ash deposits in the engine. These ash depositslower engine performance by fouling spark plugs and valves, andcontributing to preignition.

Different detergents act variously to inhibit the formation of deposits.Some detergents react chemically with deposit precursors to formharmless compounds which are solubilized in the lubricating oils. Otherdetergents prevent the coagulation of solid particles in the oil bydispersing such particles and keeping them suspended in the oil.

The compounds described herein are metal-free detergents which performboth of the above functions, namely, react chemically with the depositprecursors and prevent coagulation of solid particles in the oils.

It is a particular object of this invention to provide lubricating oilcompositions which are compounded with a metal-free detergent.

Therefore, in accordance with this invention, it has 3,l52,0ii0 FatentedOct. 6, 1964 been discovered that lubricating oil compositionsparticularly useful for heavy duty service are obtained by incorporatingacyl bis-[,B-(Z-aliphatic imidazolyl)ethyl] amines in oils oflubricating viscosity. For simplicity, these acyl bis-[,B-(Z-aliphaticimidazolyl)ethyl] amines will hereinfater be termedamido-bis-imidazolines.

By the use of lubricating oil compositions containing theamido-bis-imidazolines described herein, diesel and gasoline engineparts remain remarkably free of deposits and varnish, even under severeoperating conditions.

The amido-bis-irnidazolines, which are believed to be new compounds, aredescribed by the formula:

wherein the Rs are radicals derived from saturated and unsaturatedaliphatic monocarboxylic acids containing from 10 to 20 carbon atoms,preferably saturated alipatic monocarboxylic acids. In the aboveformula, the Rs are preferably alkyl radicals containing from 9 to 19carbon atoms.

The monocarboxylic acids from which the Rs are derived are exemplifiedby lauric acid, myristic acid, palmitic acid, stearic acid, arachidicacid, palmitoleic acid, oleic acid, elaidic acid, etc.

Lubricating oils which can be used as base oils for the compositionsdescribed herein include a wide variety of lubricating oils, such asnaphthenic base, paraflin base, and mixed base lubricating oils, otherhydrocarbon lubricants, e.g., lubricating oils derived from coalproducts, and synthetic oils, e.g., alkylene polymers (such as polymersof propylene, butylene, etc., and the mixtures thereof), alkyleneoxide-type polymers (e.g., propylene oxide polymers) and derivatives,including alkylene oxide polymers prepared by polymerizing the alkyleneoxide in the presence of water or alcohols, e.g., ethyl alcohol,dicarboxylic acid esters (such as those Which are prepared byesterifying such dicarboxylic acids as adipic acid, azelaic acid,suberic acid, sebacic acid, succinic acid, fumaric acid, maleic acid,etc., with alcohols such as butyl alcohol, hexyl alcohol, 2-ethyl hexylalcohol, dodecyl alcohol, etc.), liquid esters of acids of phosphorus,alkyl benzenes, (e.g., monoalkyl benzene such as dodecyl benzene,tetradecyl benzene, etc., and dialkyl beruenes (e.g., biphenyls andterphenyls), alkyl biphenyl ethers, polymers of silicon (e.g.,tetraethyl silicate, tetraisopropyl silicates, tetra(4-methyl-Z-tetraethyl) silicate, hexyl(4-methyl-2-pentoxy) disiloxane,poly(methyl) siloxane, poly(methylphenyl) siloxane, etc.

The above base oils may be used individually or in combinations thereof,wherever miscible or wherever made so by the use of mutual solvents.

The amido-bis-irnidazolines can be used in oils of lubricating viscocityin amounts of O.l% to 15%, by weight, preferably 0.25% to 5%, by weight.In the formation of lubricating oil concentrates thereof, amounts up to60% and greater can be incorporated in lubricating oils.

The amido-bis-imidazolines described herein can be obtained in one stepby reacting 1 mol of tetraethylenepentamine with 3 mols of an aliphaticmonocarboxylic acid at temperatures in excess of 200 C. Alternately, abisirnidazoline can be formed by first reacting 1 mol oftetraethylenepentamine with 2 mols of an aliphatic monocarboxylic acidat a temperature of at least 225 C., then reacting 1 mol of theresulting bis-imidazoline further with 1 mol of aliphatic monocarboxylicacid to yield the amido-bis-imidazoline.

The GD Nos. refer to the percentage deposits in the piston ring grooves;a evaluation being a clean groove; and a number of 100 being a groovefull of deposits.

The base oil was a California SAE base oil.

The preparation of amido-bis-imidazolines is illustrated in thefollowing example.

EXAMPLE I Preparation of Octadecanoyl Bis-[B-(Z-HeptadecylImidazolyl)Ethyl] Amine A mixture of 95 grams of tetraethylenepentamine(0.5 mol), 304 grams of actadecanoic acid (1 mol), and 150 cc. oftoluene was agitated in a glass reaction vessel for several hours at atemperature of 160 C. This resulted in the liberation of 28 cc. of waterwhich compares favorably with the amount of water produced by theformation of one imidazoline ring (27 cc. water). The mixture was thenheated for 24 hours at temperatures between 238 C. and 274 C. At the endof 24 hours, cc. of water was collected. This corresponds to atheoretical value of 36 cc. for dehydration to produce two imidazolinerings. The reaction mixture was heated to 177 C. at 5 mm. of mercurypressure to remove the toluene.

A mixture of 72 grams (0.1 mol) of the above bisimidazoline, 30 grams(0.1 mol) of octadecanoic acid, and 100 cc. of toluene was then agitatedat a temperature of about 200 C. for several hours. Two centimeters ofwater were collected in the trap, and this corresponds exactly with thetheoretical amount of water expected for the amidization of thebis-imidazoline. The resulting product was heated to a temperature of177 C. at 4 mm.

of mercury pressure to remove the toluene.

Table I hereinbelow presents data on the effectiveness ofamido-bis-imidazolines as lubricating oil additives.

The tests were made in a Caterpillar L-1 engine according to SupplementI conditions for a perior of 120 hours as described in the CoordinatingResearch Council Handbook, January 1946.

The PD Nos. refer to the piston discoloration rating. After the enginetest, the three piston lands are examined visually. To a piston skirtwhich is completely black is assigned a PD number of 800; to one whichis completely clean, a PD number of 0; to those intermediate betweencompletely black and completely clean are assigned PD numbersintermediate in proportion to the extent and degree of darkening.

In addition to illustrating the elfectiveness of theamidobis-imidazolines as lubricating oil additives, the above data showthat these amido-bis-imidazolines are markedly superior todiamido-imidazolines.

In addition to the amido-bis-imidazolines described hereinabove, thelubricating oil compositions of this invention may also contain otherdetergents, viscosity index improving agents, rust inhibitors, oilinessagents, grease thickening agents, etc.

We claim:

1. A lubricating oil composition comprising a major proportion of an oilof lubricating viscosity, and from about 0.1% to about 15% by weight ofan acyl bis-[)8- (2-alkyl-imidazolyl)ethyl] amine, wherein said alkylradical contains from 9 to 19 carbon atoms, and said acyl radicalcontains from 10 to 20 carbon atoms, said amine being prepared by firstreacting 1 mole of tetraethylene pentamine with 2 moles of alkylmonocarboxylic acid at a temperature of at least 225 C. and thenreacting 1 mole of the resulting bis-imidazoline further with 1 mole ofalkyl monocarboxylic acid.

2. A lubricating oil composition consisting essentially of an oil oflubricating viscosity, and from about 0.1% to 15% by weight of an acylbis-[fi-Z-alkyl-imidazolyl) ethyl] amine, wherein said alkyl radicalcontains from 9 to 19 carbon atoms, and said acyl radical contains from10 to 20 carbon atoms, said amine being prepared by first reacting 1mole of tetraethylene pentamine with 2 moles of alkyl monocarboxylicacid at a temperature of at least 225 C. and then reacting 1 mole of theresulting bisimidazoline further with 1 mole of alkyl monocarboxylicacid.

References Cited in the file of this patent UNITED STATES PATENTS2,622,067 White et al Dec. 16, 1952 2,647,125 Gunderson July 28, 19532,759,894 Matuszak Aug. 21, 1956 2,783,206 Messina Feb. 26, 19572,846,440 Hughes Aug. 5, 1958 2,895,961 Hughes July 21, 1959 3,018,250Anderson et al Jan. 23, 1962

1. A LUBRICATING OIL COMPOSITION COMPRISING A MAJOR PROPORTION OF AN OILOF LUBRICATING VISCOSITY, AND FROM ABOUT 0.1% TO ABOUT 15% BY WEIGHT OFAN ACYL BIS-(B(2-AKLYL-IMIDAZOLYL)ETHYL) AMINE, WHEREIN SAID ALKYLRADICAL CONTAINS FROM 9 TO 19 CARBON ATOMS, AND SAID ACYL RADICALCONTAINS FROM 10 TO 20 CARBON ATOMS, SAID AMINE BEING PREPARED BY FIRSTREACTING 1 MOLE OF TETRAETHYLENE PENTAMINE WITH 2 MOLES OF ALKYLMONOCARBOXYLIC ACID AT A TEMPERATURE OF AT LEAST 225*C. AND THENREACTING 1 MOLE OF THE RESULTING BIS-IMIDAZOLINE FURTHER WITH 1 MOLE OFALKYL LMONOCARBOXYLIC ACID.